Changes in pulmonary clearance of technetium labelled DTPA during haemodialysis.

An index of pulmonary epithelial permeability has been studied in 12 patients with chronic renal failure during haemodialysis. It was assessed by the half time clearance from lung to blood (t 1/2 LB) of a nebulised solution containing technetium labelled diethylene triamine pentacetic acid (99mTc DTPA). Six patients were cigarette smokers and six were non-smokers. The non-smokers had greater predialysis permeability (mean 37.7, range 24-54 min) than non-smokers without renal disease (mean 60.2, range 38-99 min; p less than 0.025). The t 1/2 LB was measured before dialysis and during the first half hour and the last half hour of dialysis in all 12 patients and also during other periods of dialysis in 10 of them. Dialysis lasted for five hours in 11 patients and four hours in one patient. There was no significant change in the t 1/2 LB of 99mTc DTPA during early dialysis; but as dialysis progressed there was a statistically significant increase in t 1/2 LB, suggesting a reduction of pulmonary epithelial permeability. These results show no increase in an index of pulmonary epithelial permeability in association with the pulmonary sequestration of neutrophils that occurs in early haemodialysis. They also suggest that in chronic renal failure the epithelial permeability is increased and that this can be modified by haemodialysis.